From: "Bob W"
-----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of
> John Sessoms
[...]
>
> I'm having a problem. When I first got the K10D back in March 2007 I
> set
> the date wrong, or perhaps failed to set the date at all. I didn't get
> the correct date set until 02Oct2007, about 6 months after I got the
> camera.
>
[...]
>
> Anyone got any ideas?
>
> There's bound to be an explanation in the way computers calculate dates
> for why it's doing this, but I can't see what it is.
what did you use to calculate the differences between the dates? If you did
it manually, did you take leap years into account? If you use a spreadsheet
or something it will give you the most accurate result. The way computers
calculate dates is not likely to be the reason for the drift you're seeing.
It could be down to the clock on the camera drifting, for example with a
weak battery.
If you're really, really bothered about it you could download all the data
into a spreadsheet, plug in your known dates as reference points, plot a
trend based on the known differences, then apply the trend to the exif dates
to get an approximate answer. Personally I would just live with it, but I
tend not to use the dates.
Yeah, that's what I'm doing, using a spread sheet. As far as I know,
neither 2006 nor 2007 were leap years. Here's how it works ...
My BASE date is the date I left for Annual Training in March of 2007. It
was a 21 day AT period. I have a copy of the orders that tell me when &
where to report, how long the duty will last, when we will return to
Home Station, etc.
That first day, we left in a convoy from the armory to our training site
at Camp Shelby. While we were lining the vehicles up, I took a photo of
one of the drivers at approximately 8:00 am on that Saturday morning:
KNOWN Date & Time 04/07/2007 08:00:00 (AM EST)
EXIF Date & Time 01/10/2006 3:04:19 AM (Timezone unknown)
Round the first KNOWN Date & Time to 08:04:19 because that many minutes
and seconds won't affect the outcome. That makes the difference 452 Days
+ 5 hours.
For an UN-Known Date & Time, I should be able to add that number to the
EXIF Date & Time and derive the true date and time for the photo, and I
have a photo I took approximately a week before:
EXIF Date & Time 01/02/2006 2:39:53 AM
ADD IN +452 05:00:00
DERIVED Date & Time = *Friday* 03/30/2007 07:39:53
PROBLEM - the subject matter of the photo is a Farmer's Market that was
held every SATURDAY at the mall where my photo-lab was located.
The photo cannot have been taken on Friday morning, it had to have been
taken on Saturday 03/31/2007, which changes the difference to 453 days.
The time at 07:39:53 works. So it has to be 453 Days + 5 Hours for this
photo.
Further on, I have a second KNOWN Date & approximate time to compare
with EXIF date & time.
The next to last day of AT was a convoy departing Camp Shelby for
Atlanta where we spent the night at Dobbins AFB. As Safety Officer, I
was "tail end Charlie".
During the convoy move, the vehicle in front of my vehicle was involved
in a minor traffic accident (mirror slap with an 18 wheeler sitting on
the shoulder of I-20). I had to create an Army Ground Accident Report
for the incident.
I recorded the TIME of the accident on the report as 9:20 AM CST. I took
photos as part of my "investigation" while we waited for the civilian
authorities.
KNOWN Date (time) 04/26/2007 09:30 (AM CST - 10:30 AM EST)
EXIF Date & Time 1/27/2006 5:30:40 AM
The difference is 454 days. Assuming the hours remained the same at +5,
the photo was taken at approximately 10:30 AM EST, so make it 454 Days +
5 Hours.
I have two additional KNOWN Date & Time pools from June 2007 that I can
draw from and they are both consistent with 454 Days + 5 Hours.
And for most of the remaining period 454 Days + 5 Hours added to the
EXIF Date & Time gives me a day of the week that I can reconcile with my
known work schedule.
It's not an insurmountable problem, I've already managed to get the
photos into file sequence.
I just want to figure out is why the date difference jumped from 453
Days to 452 Days and then jumped back to 454 Days?
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